During the 4/1/80-3/31/81 grant year the spectral resolution of a visible wavelength Fourier transform photoacoustic spectrometer (FTPAS), whose principal components are a home-made Michelson interferometer and a Terak minicomputer system, will be improved to make possible the rapid quantitative measurement of oxyhemoglobin, carboxyhemoglobin, and methemoglobin in whole human blood. The possibility that laser photoacoustic spectroscopy may have some advantages over the FTPAS in this particular application will be explored experimentally. The feasibility of microscopic FTPAS experiments that would provide absorption versus wavelength data for diffraction limited sample spot sizes will also be investigated.